1-) Planer Type
Milling Machine
It is called
planer-type milling machine since it resembles a double housing planning
machine in appearance, construction and to some extent its working. The main
difference between this machines is in the tool heads. In this machine
motor-driven spindle carriers are mounted on cross-rails. This is the largest
sized milling machine and is used for milling heavy components.
Milling
operations on this machine are carried out by;
a- Moving the table
against rotating cutters.
b- Feeding the
cutters by moving the milling heads against the stationary table.
c- Moving the table
and milling heads simultaneously.
These machines
are suitable for machining flat surfaces of very heavy workpieces.
(Bawa H.S.,
Manufacturing Processes – I, Pg: 90)
2-) Band Filling
and Polishing Machines
Band filing and
polishing is another variation for band machines. When the machine is to be
used for filing work, a file band replaces a saw band. The file band is
constructed of files mounted on a flexible steel band. A snap joint is provided
for quick fastening and unfastening for internal filing. A light to medium pressure
is used on contour filing, and the filing speeds range from 50 to 200 ft/min
(0.3 to 1.0 m/s). An advantage of filing is the continuous downward stroke. The
absence of a backstroke greatly engthens
the life of the file and helps in holding the work onto the table.
Files used on
this machine have the same materials, forms, and styles found on standard commercial
files. Single cut, double cut, and rasp cut are the terms used in describing the
cut of the file. Rasp cut differs from the other two in that the teeth are
disconnected from each other, each tooth being made by a single punch. The
coarseness of the teeth is described by the terms rough, coarse, bastard, double
cut, and smooth. File cross sections are indicated by such terms as flat, oval,
half round, and mill.
(Ostwald P.F.
Munoz J., Manufacturing Processes and Systems, Pg: 210)
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